@inproceedings{ijcai1971p50,
  title     = {An Algebraic Definition of Simulation Between Programs},
  author    = {Milner, Robin},
  booktitle = {Proceedings of the Second International Joint Conference on
               Artificial Intelligence, {IJCAI-71}},
  publisher = {International Joint Conferences on Artificial Intelligence},
  editor    = {D.C. Cooper},
  pages     = {481--488},
  year      = {1971},
  url       = {https://ijcai.org/proceedings/1971/50},
}